1. Field of the Invention
The present invention relates to a portable scanner for reading an image of an object to be read such as barcode symbols, and the like using a light source such as a laser beam, LED, or the like.
2. Description of the Related Art
As handy type scanners for optically reading an image of an object to be read such as a barcode, a touch scanner which utilizes a light-emitting diode (to be abbreviated as an LED hereinafter) as a light source, a laser scanner which utilizes a laser beam with a strong directivity, and the like are available.
The touch scanner comprises an LED and a light-receiving unit in its scanner main body. Light emitted from the LED is output from the exit opening of the scanner main body, and is irradiated onto a barcode. The light reflected by the barcode is received by the light-receiving unit to optically read the barcode. Since this touch scanner must read a barcode in a state wherein the distal end portion of the scanner main body covers the barcode, the readable distance is as small as 0 to 50 mm from the distal end of the scanner main body. Note that this touch scanner has an exit opening on the lower surface, on the distal end side, of the scanner main body, and a light-shielding portion for preventing the light-receiving unit from being influenced by external light extends almost vertically around the exit opening.
The laser scanner comprises a laser light source (to be referred to as a laser oscillator hereinafter), a scanning mirror, a light-receiving unit, and the like in its scanner main body. A laser beam emitted from the laser oscillator is output from the exit port of the scanner main body while being periodically oscillated by the scanning mirror, and is scanned on a barcode separated therefrom. The laser beam reflected by the barcode is received by the light-receiving unit, thereby reading the barcode separated from the scanner by a given distance. Since this laser scanner uses the laser beam with a strong directivity, the distance from the exit opening of the scanner main body to the shortest reading position is as large as several cm to several tens cm, and gun type (pistol type) scanners are popular to allow easy aiming with respect to a barcode separated therefrom.
However, since the above-mentioned touch scanner cannot accurately read a barcode unless the distal end portion of the scanner main body is brought close to or into contact with the barcode to cover it, it cannot read a barcode separated therefrom. In addition, although the touch scanner can read a barcode which is slightly larger than the exit opening of the distal end portion of the scanner main body, it cannot read a barcode larger than such a barcode. Furthermore, since a barcode in reading cannot be visually observed, the reading position cannot be confirmed.
The above-mentioned laser scanner can satisfactorily read a barcode separated therefrom by a given distance since it uses a laser beam with a strong directivity. However, the laser scanner cannot read a barcode in a state wherein the distal end portion of the scanner main body is brought close to or into contact with the barcode. In addition, when a barcode is set vertically, it can be easily read since the scanner main body can be held almost horizontally. However, when a barcode is set horizontally, the scanner main body must be held almost vertically, and is not easy to hold, resulting in difficult alignment of the scanner main body to the barcode, poor operability, and difficult reading operation.